51

Pin Descriptions

28 PIN

PLCC

24 PIN

DIP/SOIC

SYMBOL

DESCRIPTION

2

1

TIP

An analog input connected to the TIP (more positive) side of the subscriber loop through a 150

Ω

feed resistor and a ring relay contact. Functions with the Ring terminal to receive voice signals from

the telephone and for loop monitoring process.

3

2

RING

An analog input connected to the RING (more negative) side of the subscriber loop through a 150

Ω

feed resistor and a ring relay contact. Functions with the Tip terminal to receive voice signals from

the telephone and for loop monitoring purposes.

43

54

Capacitor #1 - Optional Capacitor used to improve power supply rejection. This pin should be left open

if unused.

65

Capacitor #3 - An external capacitor to be connected between this terminal and analog ground. Re-

value is 0.3

µF, 30V.

76

DG

(Note 5)

Digital Ground - To be connected to zero potential and serves as a reference for all digital inputs and

outputs on the SLIC.

9

7

RS

Ring Synchronization Input - A TTL - compatible clock input. The clock should be arranged such that

a positive transition occurs on the negative going zero crossing of the ring voltage source, ensuring

that the ring relay is activated and deactivated when the instantaneous ring voltage is near zero. If

synchronization is not required, tie to 5V.

10

8

RD

Relay Driver - A low active open collector logic output. When enabled, the external ring relay is

energized.

11

9

TF

Tip Feed-Alow impedance analog output connected to the TIP terminal through a 150

Ω feed

resistor. Functions with the RF terminal to provide loop current, feed voice signals to the telephone

set, and sink longitudinal current.

12

10

RF

Ring Feed - A low impedance analog output connected to the RING terminal through a 150

Ω feed

resistor. Functions with the TF terminal to provide loop current, feed voice signal to the telephone

set, and sink longitudinal current.

13

11

42V to -58V. Frequently referred to as “battery”.

14

12

BG

(Note 1)

Battery Ground - To be connected to zero potential. All loop current and some quiescent current

flows into this ground terminal.

16

13

SHD

Switch Hook Detection - A low active LS TTL - compatible logic output. This output is enabled for

loop currents exceeding 10mA and disabled for loop currents less than 5mA.

17

14

GKD

Ground Key Detection - A low active LS TTL - compatible logic output. This output is enabled if the

DC current into the ring lead exceeds the DC current out of the tip lead by more than 20mA, and

disabled if this current difference is less than 10mA.

18

15

PD

Power Denial - A low active TTL - Compatible logic input. When enabled the switch hook detect

(SHD) and ground key detect (GKD) are not necessarily valid, and the relay driver (RD) output is

disabled.

19

16

RC

Ring Command - A low active TTL - Compatible logic input. When enabled, the relay driver (RD)

output goes low on the next rising edge of the ring sync (RS) input, as long as the SLIC is not in the

power denial state (PD = 0) or the subscriber is not already off- hook (SHD = 0).

20

17

Capacitor #2 - An external capacitor to be connected between this terminal and digital ground.

Prevents false ground key indications from occurring during ring trip detection. Typical value is

0.15

µF, 10V. This capacitor is not used if ground key function is not required.

21

18

OUT

The analog output of the spare operational amplifier.

23

19

-IN

The inverting analog input of the spare operational amplifier.

HC-5502B